Hemlock Propagation

Seeds

• Hemlock tree seeds ripen inside cones, which turn from green to brown, and are dispersed from the tree with small wings. According to the USDA Forest Service, the germination rate is less than 25 percent, with many seeds being nonviable. For best germination results, store the seeds at a cold temperature for 10 weeks. This is called stratification. In natural conditions, hemlock seeds respond to winter chill and develop in the spring, often germinating on the soil surface.

Germination

• To germinate, seeds require a warm, moist growing spot with a mix of organic matter and mineral soil. Without such soil, seedlings will grow on rotten logs, mounds and stumps that have a warmer surface and optimum moisture retention, as opposed to the forest floor. A temperature of 59 degrees Fahrenheit is ideal for germination, but a high rate of germination will result from temperatures ranging from 44 to 64 degrees Fahrenheit.

Growth

• Hemlock trees develop slowly and are susceptible to diseases and problems as they are establishing. During the first year, seedlings may reach just 1 to 1 1/2 inches in height. They are susceptible to drying out until their root reaches a sufficient depth, at which point they grow much faster. Due to this sensitivity to moisture stress, seedlings generally thrive best under forest understory and may dry out if grown out in the open or under thin cover. Damping off or root rot may occur, but can be controlled with the use of fungicides.

Vegetative Propagation

• Most nursery-grown plants are produced from seed. Usually hemlock trees are not propagated vegetatively, or with rooted cuttings, unless for ornamental production. Use auxin treatments to induce rooting in stem cuttings grown in greenhouses. Trees replant successfully in natural forest canopy cover, but tend to thrive best when planted under somewhat dense forest cover.